This invention relates to a noncopiably but reproducibly recorded videotape, and to a video signal recording system capable of recording video signal on a videotape noncopiably therefrom to other videotapes but reproducibly on a television receiver through a usual videotape playback apparatus.
In one of the conventional common methods of recording video signals on a videotape noncopiably therefrom to another tape, recording is made with vertical synchro signals kept at a level lower than a normal level. In trying to copy the signals recorded in such a manner to another videotape with a usual video recorder, the synchro signal separator of the recorder cannot be properly operatd because of the deliberate weakness of the vertical sysnchro signals. But it is no problem to reproduce the recorded video signals on a television picture screen by increasing the vertical synchro signals to a normal level by means of a vertical synchro signal controller incorporated in most of the television receiving apparatus.
However, the prior art system has the following disadvantages:
(1) If the synchro signal controller of a video-tape recorder has a sufficient sensitivity to allow the video signals to be reproduced on another videotape, the original videotape is in danger of being pirated;
(2) It is troublesome to adjust the vertical synchro signal controller each time when the videotape is played back on a television receiving set;
(3) It may happen that the video signals cannot be reproduced because the maximum adjustable level of the vertical synchro signal controller of the televeision receiving set is low; and
(4) If the television receiving is not provided with a synchro signal controller, it is absolutely impossible for the videotape to be played back.